JP2007009171A - Evoh-based composite resin and hose for transporting coolant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EVOH-based composite resin capable of realizing a hose for transporting a coolant, extremely excellent in gas barrier property and flexibility, and also in endurance performance such as impulse resistance property after a long term heat aging, vibration endurance test after the impulse test, dynamic endurance test after the heat aging, etc., and the hose for transporting the coolant by using the EVOH-based composite resin. <P>SOLUTION: This EVOH-based composite resin is provided by containing an ethylene-vinyl alcohol copolymer and an elastomer. The EVOH-based composite resin excellent in gas barrier property, flexibility and durability is realized by adding an elastomer as a flexibility-imparting agent to make a polymer alloy of the EVOH-based composite resin. The hose for transporting the coolant having a layer consisting of the EVOH-based composite resin is also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is excellent in flexibility and gas barrier properties, and by using this as the innermost layer of a refrigerant transport hose, a refrigerant transport hose excellent in gas barrier properties (refrigerant permeability), dynamic durability, and flexibility can be obtained. The present invention relates to an EVOH composite resin that can be provided, and a refrigerant transport hose using this EVOH composite resin.

  Refrigerant transport hoses used for piping and the like of automobile air conditioners are roughly classified into high pressure lines and low pressure lines. The high-pressure line is a line that supplies high-temperature refrigerant compressed into a gas-liquid mixture by a compressor to the condenser at high pressure. The low-pressure line is a line for returning the low-pressure / low-temperature refrigerant evaporated by the evaporator to the compressor.

  The refrigerant transport hose has excellent gas barrier properties that can reliably prevent the leakage of refrigerant (Freon), flexibility to ensure the routing of the refrigerant transport hose in narrow spaces, and durability Properties such as aging resistance, impact resistance, and mechanical strength are required, but especially for gas barrier properties, the amount of refrigerant leakage in the high-pressure line is significant due to its mechanism, so high gas barrier properties are required. It has been.

  The conventional refrigerant transport hose has an innermost layer made of a composite resin obtained by adding an elastomer as a flexibility-imparting agent to a polyamide-based resin such as polyamide 6 (nylon 6) in order to ensure gas barrier properties and flexibility. It is arranged as a gas barrier layer and has a multilayer structure in which a rubber layer is coated on the outer periphery. In the innermost layer, although the flexibility is improved by blending the elastomer, the gas barrier property of the elastomer itself is inferior to that of polyamide, and as a result, the gas barrier property of the innermost layer made of the composite resin is impaired.

  Therefore, in order to solve this problem, the present applicant firstly used a refrigerant transport hose excellent in gas barrier properties and flexibility, in which the innermost layer was polyamide 6:58 to 72 parts by weight and elastomer: 42 to 28 parts by weight. Proposing a refrigerant transport hose comprising a sea-island-structured resin layer in which the sea phase is polyamide 6, the island phase is elastomer, and the polyamide 6 is dispersed in the island phase of the elastomer (Japanese Patent Laid-Open No. 2000-120944).

  In this refrigerant transport hose, since the innermost resin layer has the polyamide 6 phase scattered in the form of scattered dots in the elastomeric island phase, the elastomeric island phase is present inside the original volume of the elastomer. The apparent volume fraction increases by the amount of the polyamide 6 phase. Thus, when the apparent volume fraction of the island phase of the elastomer is increased, the same effect of improving the flexibility as when the amount of the elastomer is increased can be obtained. For this reason, the blending amount of the actual elastomer can be kept low, and therefore a good flexibility improvement effect can be obtained without causing a decrease in gas barrier properties due to the blending of the elastomer.

  In recent years, environmental problems have been greatly taken up, and the global warming potential of Freon gas R-134a, which is used as a refrigerant in automobile coolers, is becoming a problem. The current Freon gas R-134a has a global warming potential of nearly 1500 although its ozone depletion coefficient is zero, and a significant reduction in the amount of leakage has been demanded.

  In response to this trend, a new fluorinated gas emission regulation proposal was adopted by the EU around the middle of 2003, and in the automobile OE companies, a significant reduction in the amount of refrigerant leakage became a major concern. The resin layer having polyamide as a main component as described in the publication No. 1 has insufficient gas barrier performance, and a drastic review has been necessary to comply with EU regulations.

  Therefore, as a refrigerant transport hose having excellent gas barrier properties and dynamic durability such as impulse resistance and flexibility, the present applicant has applied a polyamide (hereinafter referred to as “polyamide MX”) as a structural unit of metaxylenediamine. Has been proposed previously (Japanese Patent Application No. 2004-104947).

  However, although polyamide MX is excellent in gas barrier performance, the material itself is very hard, so that it can sufficiently satisfy the durability performance such as impulse resistance after long-term heat aging and vibration durability test required for a hose. Absent. Therefore, in Japanese Patent Application No. 2004-104947, the polyamide MX layer having excellent gas barrier properties is provided as the gas barrier layer, and the resin layer responsible for flexibility and dynamic durability is provided as the innermost layer, thereby solving the above-mentioned problems.

  For this reason, in Japanese Patent Application No. 2004-104947, it is necessary to have a multilayer structure of a polyamide MX layer responsible for gas barrier properties and a resin layer responsible for flexibility and durability. In production, high production technology and expensive multilayer extrusion are required. There is a problem of requiring equipment.

  Therefore, as a polyamide MX-based composite resin that is excellent in gas barrier properties and sufficiently excellent in flexibility and durability, and can form a good gas barrier layer of a refrigerant transport hose without having a multilayer structure, The applicant previously proposed a polyamide-based composite resin containing polyamide MX and polyolefin (Japanese Patent Application No. 2004-299025).

If the EVOH composite resin of Japanese Patent Application No. 2004-299025, which is a polymer alloy by adding polyolefin as a flexibility imparting agent to polyamide MX, a polyamide composite resin excellent in gas barrier properties, flexibility, and durability is realized. The
JP 2000-120944 A Japanese Patent Application No. 2004-104947 Japanese Patent Application No. 2004-299025

  The polyamide MX composite resin described in Japanese Patent Application No. 2004-299025 is excellent in gas barrier properties, flexibility, and durability, but further improvement is desired. In particular, since it is inferior to ordinary polyamide to have sufficient gas barrier properties and durability with a thinner film thickness, it is preferable in maintaining flexibility, so improvement of this point is desired. It is rare.

  The present invention has been made in view of the above circumstances, and is excellent in gas barrier properties and flexibility, and has an impulse resistance performance after long-term heat aging, a vibration durability test after an impulse test, and a dynamic durability test after heat aging. An object of the present invention is to provide an EVOH composite resin capable of realizing a refrigerant transport hose excellent in durability performance such as the above, and a refrigerant transport hose using the EVOH composite resin.

As a result of intensive studies to solve the above problems, the present inventor has paid attention to a copolymer of ethylene and vinyl alcohol, which is excellent in gas barrier performance, and further, while minimizing the deterioration of the gas barrier performance, flexibility has been achieved. By examining and adding an elastomer as a flexibility-imparting agent to an ethylene / vinyl alcohol copolymer (EVOH) to make a polymer alloy, the flexibility can be remarkably improved while suppressing a decrease in gas barrier properties. The present inventors have found that the durability performance required for refrigerant transport hoses, such as impulse resistance after long-term heat aging, vibration durability test after impulse test, and dynamic durability test after heat aging, can be sufficiently satisfied.
The present invention has been achieved based on such knowledge, and the gist thereof is as follows.

[1] An EVOH composite resin comprising an ethylene / vinyl alcohol copolymer and an elastomer.

[2] The EVOH composite resin according to [1], wherein the elastomer content is 10 to 45% by weight.

[3] An EVOH composite resin according to [2], wherein the elastomer is a modified elastomer or a mixture of a modified elastomer and an unmodified elastomer.

[4] The EVOH composite resin according to [1] to [3], wherein the content of the modified elastomer is 20% by weight or less.

[5] The EVOH composite resin according to [1] to [4], wherein an average acid value of the entire elastomer is ₃ to 7.5 mg-CH ₃ ONa / g.

[6] An EVOH composite resin according to [3] to [5], wherein the modified elastomer has an acid value of ₃ to 15.0 mg-CH ₃ ONa / g.

[7] In [1] to [6], the sea phase is an ethylene / vinyl alcohol copolymer, the island phase is an elastomer, and the ethylene / vinyl alcohol copolymer is dispersed in the island phase of the elastomer. An EVOH-based composite resin characterized by being dispersed in the form of dots.

[8] The EVOH composite resin according to [1] to [7], wherein the ethylene / vinyl alcohol copolymer has an ethylene content of 28 to 40 mol%.

[9] A refrigerant transport hose comprising a layer made of the EVOH composite resin according to any one of [1] to [8].

  According to the present invention, an EVOH composite resin having excellent gas barrier properties, flexibility, and durability is realized by adding an elastomer as a flexibility-imparting agent to a polymer alloy by adding an ethylene-vinyl alcohol copolymer. The Therefore, according to the refrigerant transportation hose in which the EVOH composite resin of the present invention is applied to the gas barrier layer, the gas barrier property and the flexibility are remarkably excellent, the impulse resistance after long-term heat aging, and the vibration after the impulse test. Provided is a refrigerant transport hose excellent in durability performance such as a durability test and a dynamic durability test after heat aging.

  Embodiments of the EVOH composite resin and refrigerant transport hose of the present invention will be described in detail below.

  First, the EVOH composite resin of the present invention will be described.

  The EVOH composite resin of the present invention is a polymer alloy obtained by adding an elastomer as a flexibility-imparting agent to an ethylene / vinyl alcohol copolymer.

  The ethylene / vinyl alcohol copolymer has an ethylene / vinyl alcohol composition ratio of a large amount of ethylene. If the amount of vinyl alcohol is small, its properties are close to that of polyethylene and its flexibility is improved, but the melting point is lowered and the gas barrier property is impaired. It is. On the contrary, when ethylene is small and vinyl alcohol is large, the flexibility is impaired, but the melting point is increased and the gas barrier property is greatly improved. Therefore, the ethylene content is preferably about 28 to 40 mol%.

  As the ethylene / vinyl alcohol copolymer, one kind may be used alone, or two or more kinds having different molecular weights and composition ratios may be used in combination.

  As the elastomer, ethylene / butene copolymer, EPR (ethylene-propylene copolymer), modified ethylene / butene copolymer, EEA (ethylene-ethyl acrylate copolymer), modified EEA, modified EPR, modified EPDM (ethylene) -Propylene-diene terpolymer), ionomer, α-olefin copolymer, modified IR (isoprene rubber), modified SEBS (styrene-ethylene-butylene-styrene copolymer), halogenated isobutylene-paramethylstyrene copolymer Examples thereof include a polymer, an ethylene-acrylic acid-modified product, an ethylene-vinyl acetate copolymer, an acid-modified product thereof, and a mixture containing them as a main component. These may be used alone or in combination of two or more.

  Elastomers, especially those modified with acid anhydrides such as maleic anhydride, alkyl acrylate esters such as glycidyl methacrylate, epoxies and modified products thereof, are fine particles based on ethylene / vinyl alcohol copolymers. An alloy structure can be obtained, which is preferable.

  If the elastomer content in the EVOH composite resin of the present invention is too small, the effect of improving the flexibility and durability due to the blending of the elastomer cannot be sufficiently obtained, and if it is too much, the gas barrier property decreases. The content in the EVOH composite resin is preferably 10 to 45% by weight, particularly preferably 10 to 35% by weight. When the content of the elastomer in the EVOH composite resin is too large, the sea phase and the island phase are reversed in the sea-island structure described later, and the gas barrier property is remarkably lowered.

When a modified elastomer such as an acid-modified elastomer is used as the elastomer, an effect that less specific energy and a high kneading technique are not required at the time of kneading (dispersion) can be obtained. When the modified elastomer is used as the elastomer, the content of the modified elastomer in the EVOH composite resin is 20% by weight or less, for example, 5 to 20% by weight. % Is preferable.
In particular, in the present invention, it is preferable that 40 to 100% by weight of the elastomer in the EVOH composite resin is an acid-modified elastomer.

By the way, originally, ethylene / vinyl alcohol copolymer and various elastomers such as the above-mentioned ethylene elastomer are not compatible. In the present invention, the object of the present invention is achieved by forming a compatible state, that is, a good dispersion state in such an incompatible system. Therefore, in order to form this compatible state, it is important that at least a part of the elastomer is modified with maleic anhydride or the like, and the average acid value of the entire elastomer used to obtain a good dispersion form The (acid modification rate) is preferably 3.0 mg-CH ₃ ONa / g or more.

The higher the acid value of the elastomer, the better the dispersion form, but the viscosity of the EVOH composite resin obtained with an increase in the acid value increases and the moldability is impaired. For this reason, in order to reduce the increase in viscosity due to the increase in the acid value, the acid value of the elastomer is preferably low in a range where a good dispersion state can be obtained, and the average acid value of the whole elastomer used is 7.5 mg. is preferably not more than -CH ₃ ONa / g.

Moreover, even if the average acid value is the same, when the acid value of the modified elastomer contained in the elastomer to be used is high, the modified elastomer is mixed with the unmodified elastomer, thereby extruding even if the average acid value is lowered. Occasionally, gel-like foreign substances appear due to local overreaction. Therefore, the acid value of the modified elastomer to be used is preferably 15.0 mg-CH ₃ ONa / g or less.

That is, for example, an acid-modified elastomer having an acid value of 30 mg-CH ₃ ONa / g and an unmodified elastomer are mixed at a weight ratio of 17:83, and the average acid value of the entire elastomer is about 5 (= 30 × 17 ÷ 100). The mixed elastomer A and the mixed elastomer B in which an acid-modified elastomer having an acid value of 10 and an unmodified elastomer are mixed at a weight ratio of 50:50 and the average acid value of the entire elastomer is 5 are obtained by using this. Even if the apparent viscosity and the dispersed particle size of the EVOH composite resin are the same, the processing stability is greatly different. In the mixed elastomer A, gel-like foreign matters are scattered at the time of extrusion, but the mixed elastomer B has good stability. Obtainable. Therefore, the acid value of the modified elastomer used is preferably 15.0 mg-CH ₃ ONa / g or less. The lower limit of the acid value of the modified elastomer is 3 mg-CH ₃ ONa / g, which is the lower limit of the average acid value of the elastomer.

  Thus, by blending an elastomer with an ethylene / vinyl alcohol copolymer, flexibility and durability are improved, but a decrease in gas barrier properties is unavoidable. However, by taking a fine alloy structure of the ethylene / vinyl alcohol copolymer and the elastomer, in particular, the island phase of the elastomer is dispersed in the sea phase of the ethylene / vinyl alcohol copolymer. The structure in which the ethylene / vinyl alcohol copolymer is dispersed in the form of dots is preferable because it can suppress a decrease in gas barrier properties due to the blending of the elastomer.

  In particular, the amount of elastomer relative to the ethylene / vinyl alcohol copolymer (the sum of the ethylene / vinyl alcohol copolymer constituting the sea phase and the ethylene / vinyl alcohol copolymer phase present in the form of dots in the island phase of the elastomer) It is preferable that the proportion of the ethylene / vinyl alcohol copolymer phase existing in the form of scattered dots in the island phase (hereinafter, the ratio is referred to as “scattered dispersion”) is about 5 to 40% by weight. If this proportion is less than 5% by weight, the effect of having the ethylene / vinyl alcohol copolymer phase present in the form of scattered dots in the island phase of the elastomer cannot be obtained sufficiently, and conversely if it exceeds 40% by weight. Further, the ethylene / vinyl alcohol copolymer phase as the sea phase is too small, and the gas barrier property may be lowered.

  The size of the elastomeric island phase and the size of the ethylene / vinyl alcohol copolymer phase in the elastomeric island phase are about 0.4 to 1.5 μm in size of the elastomeric island phase. The size of the polymer phase is preferably about 0.05 to 0.5 μm.

  The EVOH composite resin of the present invention may contain a resin component other than the ethylene / vinyl alcohol copolymer as a resin component. In that case, of the all resin components in the EVOH composite resin, 70% by weight or more is preferably an ethylene / vinyl alcohol copolymer for securing gas barrier properties.

  Examples of other resin components in this case include one or more of polyamide resins.

  Moreover, you may add additives, such as anti-aging agent and an oxidative degradation agent, to the EVOH type composite resin of this invention as needed.

  By the way, considering the processability of EVOH composite resin, especially the extrusion stability in a thin film, the fluidity of EVOH composite resin is important and measured at 250 ° C. under a load of 5005 g in accordance with ASTM D1238. The MFR value (hereinafter referred to as “MFR (250 ° C./5005 g)”) is preferably 3.0 or more. Although there is no restriction | limiting in particular about the upper limit of MFR (250 degreeC / 5005g) of this EVOH type composite resin, Usually, it is 20 or less.

The EVOH composite resin of the present invention, particularly the EVOH composite resin having a sea-island structure as described above, can be produced by, for example, the following method (1) or (2).
(1) A method in which an ethylene / vinyl alcohol copolymer and an elastomer are kneaded at a predetermined blending ratio to form a master batch, and then the master batch and the ethylene / vinyl alcohol copolymer are kneaded.
(2) A method of melt kneading an ethylene / vinyl alcohol copolymer and an elastomer blend by high shear.

  Next, the refrigerant transport hose of the present invention having such a layer made of the EVOH composite resin of the present invention will be described with reference to the drawings.

  1 and 2 are perspective views showing an embodiment of the refrigerant transport hose of the present invention, and FIGS. 3A to 3D are other embodiments of the resin layer of the refrigerant transport hose according to the present invention. It is a perspective view which shows a form.

  In the refrigerant transport hose 10 of FIG. 1, the reinforcing yarn layer 3 is formed between the inner rubber layer 2 and the outer rubber 5, and the resin layer 1 is formed on the inner periphery of the inner rubber layer 2. The reinforcing yarn layer 3 includes a first reinforcing yarn layer 3A in which the reinforcing yarn is wound in a spiral shape, and a second reinforcing yarn layer 3B in which the reinforcing yarn is wound in a spiral shape in a direction opposite to the first reinforcing yarn layer 3A. The intermediate rubber layer 4 is laminated. An adhesive layer may be provided between the resin layer 1 and the inner tube rubber layer 2 as necessary.

  In the refrigerant transport hose 10A of FIG. 2, the inner rubber layer 6 is further formed as the innermost layer on the inner layer of the resin layer 1 in the refrigerant transport hose 10 of FIG. An adhesive layer may be provided between the inner rubber layer 6 and the resin layer 1 as necessary.

  The resin layer 1 is composed of the above-described EVOH composite resin of the present invention. The thickness of the resin layer 1 is preferably as thick as possible in terms of the gas barrier properties and durability of the hose. On the other hand, when the thickness of the resin layer 1 is increased, the flexibility of the hose is sacrificed. Therefore, the thickness of the resin layer 1 is preferably 20 to 300 μm, particularly 50 to 100 μm.

  The resin layer 1 made of the EVOH composite resin of the present invention has a single-layer structure, an impulse resistance after long-term heat aging as a layer laminated on the innermost layer of the refrigerant transport hose or the inner rubber layer as the innermost layer. The EVOH system of the present invention can provide a refrigerant transport hose having excellent durability performance such as vibration durability test after impulse test and dynamic durability test after heat aging, and excellent gas barrier performance. A refrigerant transport hose using a composite resin can be easily manufactured without the need for co-extrusion for forming a multilayer structure.

  However, in the refrigerant transport hose of the present invention, the resin layer does not necessarily have a single-layer structure as shown in FIGS. 1 and 2, and the total thickness of the hose is excessively increased to reduce flexibility and increase costs. As long as the weight does not increase, as shown in FIGS. 3A to 3D, the resin layers may be laminated resin layers 1A to 1D. 3A to 3D show laminated resin layers 1A and 1B as an alternative to the resin layer 1 of the refrigerant transport hose 10 in FIG. 1, and the other configurations are the same. Further, an inner tube rubber layer 2, an intermediate rubber layer 4 and a jacket rubber 5 are formed on the laminated resin layers 1A and 1B as in FIG. 1, and an inner rubber layer 6 is provided as in FIG.

  The laminated resin layer 1A in FIG. 3A is laminated in the order of the first resin layer 1a-1, the second resin layer 1b, and the first resin layer 1a-2 from the inner side, and has an alternate laminated structure of three layers. 3B, the laminated resin layer 1B of FIG. 3B includes a first resin layer 1a-1, a second resin layer 1b-1, a first resin layer 1a-2, and a second resin layer from the inside. This is a five-layered alternately laminated structure in which the resin layer 1b-2 and the first resin layer 1a-3 are laminated in this order. The laminated resin layer 1C in FIG. 3C has a two-layer laminated structure in which the second resin layer 1b and the first resin layer 1a are laminated in this order from the inside, and the laminated layer in FIG. The resin layer 1D has a two-layer laminated structure in which the first resin layer 1 and the second resin layer 1b are laminated in this order from the inside.

  Here, the first resin layers 1a, 1a-1, 1a-2, 1a-3 are layers mainly responsible for durability and flexibility, preferably polyamide 6:58 to 72 parts by weight and elastomer: 42 to 28 parts by weight (however, the total of polyamide 6 and elastomer is 100 parts by weight), and the elastomeric island phase is dispersed in the sea phase of polyamide 6 and the polyamide 6 is contained in the island phase of this elastomer. It consists of a polyamide 6-elastomer composite resin having a structure dispersed in the form of scattered dots. Here, if the polyamide 6 of the polyamide 6-elastomer composite resin is less than 58 parts by weight, the gas barrier property is inferior even if the morphology of the specific sea-island structure is used. On the other hand, when the amount of polyamide 6 is more than 72 parts by weight, even if it is a morphology of the specific sea-island structure, the flexibility is inferior.

  Further, even when the polyamide 6-elastomer composite resin is in the composition range of the specific polyamide 6-elastomer, when the specific sea-island structure morphology is not exhibited, good gas barrier properties and flexibility can be obtained. Can not. In order to make this gas barrier property and flexibility both the best, especially for polyamide 6 (the total of polyamide 6 constituting the sea phase and the polyamide 6 phase existing in the form of scattered dots in the island phase of the elastomer). It is preferable that the ratio of the polyamide 6 phase existing in the form of dots in the island phase of the elastomer (hereinafter, the ratio is referred to as “spot-like dispersion ratio”) is about 2.5 to 30% by weight. If this proportion is less than 2.5% by weight, the above-mentioned effect due to the presence of the polyamide 6 phase in the form of scattered dots in the island phase of the elastomer cannot be sufficiently obtained. Conversely, if it exceeds 30% by weight, The polyamide 6 phase as the sea phase is too small and the gas barrier property may be lowered.

  The size of the elastomeric island phase and the size of the polyamide 6 phase in the elastomeric island phase are approximately 0.4 to 1.5 microns for the elastomeric island phase and 0. It is preferable that it is about 05-0.5 micron.

  As the elastomer, ethylene / butene copolymer, modified ethylene / butene copolymer, EEA (ethylene-ethyl acrylate copolymer), modified EEA, modified EPR (ethylene-propylene copolymer), modified EPDM (ethylene-propylene) -Diene terpolymer), ionomer, α-olefin copolymer, modified IR (isoprene rubber), modified SEBS (styrene-ethylene-butylene-styrene copolymer), halogenated isobutylene-paramethylstyrene copolymer , Ethylene-acrylic acid-modified products, ethylene-vinyl acetate copolymers, acid-modified products thereof, and mixtures containing these as main components. These may be used alone or in combination of two or more.

  You may add additives, such as anti-aging agent and an oxidative degradation agent, to this polyamide 6-elastomer type composite resin as needed.

In addition, as a method of forming the morphology of the specific sea-island structure of the polyamide 6-elastomer composite resin,
(1) A method in which polyamide 6 and elastomer are kneaded at a predetermined mixing ratio to form a master batch, and then the master batch and polyamide 6 are kneaded.
(2) A method of melt-kneading polyamide 6 and an elastomer blend by high shear.
Etc.

  The second resin layers 1b, 1b-1, and 1b-2 are layers mainly responsible for gas barrier properties and are composed of the EVOH composite resin of the present invention.

  In the laminated resin layer 1A having a three-layer laminated structure shown in FIG. 3A, the first resin layers 1a-1 and 1a-2 each have a film thickness of 30 to 200 μm, and the second resin layer 1b has a film thickness of 20 respectively. It is preferable to be set to ˜80 μm. Moreover, in the laminated resin layer 1B having a five-layer laminated structure shown in FIG. 3B, the first resin layers 1a-1 and 1a-3 each have a thickness of 20 to 100 μm, and the first resin layer 1a-2. It is preferable that the film thickness of the second resin layer 1b-1 and 1b-2 is 20 to 80 μm. In the laminated resin layer 1C having a two-layer structure shown in FIG. 3C, the film thickness of the second resin layer 1b is 30 to 200 μm, and the film thickness of the first resin layer 1a is 20 to 80 μm. preferable. 3D, the first resin layer 1a has a thickness of 20 to 80 [mu] m, and the second resin layer 1b has a thickness of 30 to 200 [mu] m. It is preferable.

  The laminated resin layer may also have a four-layer laminated structure of first resin layer / second resin layer / first resin layer / second resin layer.

  The laminated resin layers 1A to 1D having such a multi-layered structure can be easily manufactured by integral molding by co-extrusion of the plurality of resin layers. In this case, polyamide and ethylene / vinyl alcohol are used. Since the copolymer is relatively familiar, the first resin layer and the second resin layer must be firmly bonded by co-extrusion, and special treatment must be performed between the layers. There is no.

  There is no restriction | limiting in particular about the other structure of the refrigerant | coolant transport hose of this invention, The structure of the normal refrigerant | coolant transport hose is employable.

  For example, in the refrigerant transport hoses 10 and 10A shown in FIGS. 1 and 2, rubbers constituting the inner tube rubber layer 2 and the jacket rubber 5 are generally butyl rubber (IIR), chlorinated butyl rubber (C1-IIR), chlorine Polyethylene, chlorosulfonated polyethylene, brominated butyl rubber (Br-IIR), isobutylene-bromoparamethylstyrene copolymer, EPR (ethylene-propylene copolymer), EPDM (ethylene-propylene-diene terpolymer) , NBR (acrylonitrile butadiene rubber), CR (chloroprene rubber), hydrogenated NBR, acrylic rubber, blends of two or more of these rubbers, or blends with polymers based on these rubbers, preferably butyl Rubber or EPDM rubber is used. These rubbers can be applied with compounding recipes such as commonly used fillers, processing aids, anti-aging agents, vulcanizing agents, and vulcanization accelerators.

  The rubber type of the inner rubber layer 2 and the rubber type of the jacket rubber 5 may be the same type or different types.

  Moreover, the rubber | gum of the intermediate | middle rubber layer 4 should just have the adhesiveness with the inner tube | pipe rubber layer 2 and the jacket rubber 5, and there is no restriction | limiting in particular.

  The reinforcing yarn is not particularly limited as long as it is usually used. In general, polyester, wholly aromatic polyester, nylon, vinylon, rayon, aramid, polyarylate, polyethylene naphthalate and blended yarns thereof are used.

  The thickness of the inner tube rubber layer 2 is preferably about 0.8 to 4 mm from the viewpoint of flexibility. Furthermore, it is preferable that the thickness of the intermediate rubber layer 4 including the reinforcing yarn is about 0.5 to 5 mm, and the thickness of the outer rubber layer 5 is about 1 to 2 mm.

  In the refrigerant transport hose 10A shown in FIG. 2, the rubber constituting the inner rubber layer 6 includes IIR, chlorinated IIR, brominated IIR, CR, NBR, hydrogenated NBR, acrylic rubber, ethylene acrylic rubber, and the like. The thickness is preferably about 0.3 to 1.5 mm.

  Such a refrigerant transport hose of the present invention is manufactured by extruding and laminating the material of each constituent layer to a predetermined thickness on a mandrel and vulcanizing at 140 to 170 ° C. for 30 to 120 minutes according to a conventional method. can do.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, comparative examples, and reference examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

  The rubber ratios of the inner rubber layer, intermediate rubber layer, and outer rubber layer used in the following examples, comparative examples, and reference examples are as shown in Tables 1 to 3 below.

Examples 1-5, Comparative Examples 1-3
A refrigerant transport hose having the configuration shown in FIG. 1 or FIG. 3 (a) was manufactured by the following procedure using the following materials for the resin layer.
Polyamide: 6 nylon “1022B” manufactured by Ube Industries, Ltd.
Ethylene / vinyl alcohol copolymer: Kuraray "L-101B"
Polyamide MX: MX nylon “S6001” manufactured by Mitsubishi Gas Chemical Company
Polyolefin: α-olefin polymer “Tuffmer A-1050” manufactured by Mitsui Chemicals, Inc.
Acid-modified polyolefin: Maleic acid-modified α-olefin polymer manufactured by Mitsui Chemicals, Inc.
"Toughmer MH7010"
EEA: Mitsui DuPont "Evaflex EEA A709"
Modified EEA: “HPR AR201” manufactured by Mitsui DuPont

<Production method 1: Production of refrigerant transport hose shown in FIG. 1>
The resin layer 1 having a thickness of 250 μm was formed on a mandrel having a diameter of 11 mm by extrusion with the resin composition shown in Table 4, and then the inner layer rubber shown in Table 1 was extruded to a thickness of 1.6 mm. On top of this, 22 polyester reinforcing yarns with a number of times of 10/10 cm at 1100 dtex / 4 were drawn and wound in a spiral shape, and the intermediate rubber shown in Table 2 was extruded to a thickness of 0.3 mm on this reinforcing yarn layer. On top of that, 22 polyester reinforcing yarns having a number of times of 10/10 cm at 1100 dtex / 4 were drawn and wound in a spiral shape in the opposite direction. Next, the jacket rubber shown in Table 3 was extruded to a thickness of 1.2 mm and vulcanized at 150 ° C. for 45 minutes to obtain a refrigerant transport hose having an inner diameter of 11 mm and an outer diameter of 19 mm.

<Production Method 2: Production of Refrigerant Transport Hose Shown in FIG. 3A>
A refrigerant transport hose is produced in the same manner as in Production Method 1 except that the resin layer by coextrusion is a laminated resin layer 1A having a three-layer structure having the following thickness and composition as shown in FIG. 3 (a). did.
First resin layer 1a-1: resin blend = resin layer material of Comparative Example 1, thickness = 150 μm
Second resin layer 1b: resin composition = resin layer material of each example shown in Table 4, thickness = 50 μm
First resin layer 1a-2: resin composition = resin layer material of Comparative Example 1, thickness = 50 μm

<Evaluation>
The obtained refrigerant transport hose was examined for flexibility, Freon gas barrier properties and impulse resistance by the following methods, and the results are shown in Table 4. Moreover, the external appearance at the time of resin layer extrusion was observed visually, and the good ((circle)) and no (x) were shown in Table 4.

  The EVOH composite resin of the resin layer in each example has an island phase of an elastomer having a diameter of about 0.5 to 2.0 μm dispersed in the sea phase of the ethylene / vinyl alcohol copolymer. Inside, an ethylene / vinyl alcohol copolymer having a diameter of about 0.04 to 0.45 μm is dispersed in the form of scattered dots, and the scattered dot dispersion obtained by transmission electron microscope images is shown in Table 4. It was street.

Flexibility:
It was measured by a three-point bending test.
The center was pushed at a load cell of 500 mm / min with a span of 200 mm between the rollers, the indentation load was measured, and the value was shown as an index when the value of Comparative Example 1 was set to 100. The smaller this value, the better the flexibility.

Freon gas barrier properties:
A predetermined amount of Freon gas was filled in the hose and left in a constant temperature bath at 90 ° C., and the weight decreased was measured every 24 hours. After the weight loss per unit time was stabilized, the amount of leakage per 1 m / day of the hose was measured and indicated as an index when the amount of leakage in Comparative Example 1 was set to 100. The lower this value, the better the gas barrier property.

Impulse resistance:
It investigated by the repeated pressurization test.
Under the conditions of 0 to 140 ° C., 0 to 3.3 MPa, and 20 CPM, the inner surface of the hose was repeatedly pressurized with PAG oil, and it was confirmed that the hose was cracked and the airtightness was ensured. The numerical values in the table are the number of repetitions (10,000 times) until the airtightness is impaired, and the larger the value, the better the impulse resistance.

From Table 4, it can be seen that according to the EVOH composite resin of the present invention, a refrigerant transport hose excellent in flexibility, gas barrier properties and durability can be obtained.
In contrast, Comparative Example 1 provided with the polyamide / elastomer composite resin layer has good flexibility but is inferior in gas barrier properties. The durability is good. In Comparative Example 2 using polyamide MX, the gas barrier property is improved, but it is not sufficient. Moreover, in the comparative example 3 which uses only an ethylene-vinyl alcohol copolymer and does not use an elastomer, flexibility and durability are inferior.
In Example 4, since a large amount of the acid-modified elastomer was blended, the appearance when the resin layer was extruded was slightly inferior, but the flexibility and gas barrier properties were excellent. However, the durability is inferior because of the early occurrence of cracks starting from the defective appearance portion. In Example 5, the amount of the elastomer is large and the flexibility is excellent, but the gas barrier property is slightly inferior. The durability was good reflecting its flexibility.

Examples 6 to 10, Comparative Examples 4 and 5, Reference Examples 1 to 5
For the second resin layer 1b (thickness 50 μm), the following materials are used in the formulation shown in Table 5, and the first resin layer 1a-1 (thickness 150 μm) and 1a-2 (thickness 50 μm) are comparative examples. A refrigerant transport hose having the configuration shown in FIG. 3A was manufactured using the resin layer material No. 2 according to the procedure of manufacturing method 2 described above.
Polyamide: 6 nylon “1022B” manufactured by Ube Industries, Ltd.
Ethylene / vinyl alcohol copolymer: Kuraray "L-101B"
EPR: JSR "EP961"
Modified EPR-1: “T7712” manufactured by JSR (acid value 0.9)
Modified EPR-2: “T7741” manufactured by JSR (acid value 4.7)
Modified EPR-3: “T7761” manufactured by JSR (acid value 7.4)
Modified EPR-4: “KA8962” manufactured by Bayer (acid value 18.5)

  About the obtained refrigerant | coolant transport hose, it carried out similarly to Example 1, and investigated the softness | flexibility, Freon gas barrier property, and impulse resistance, and the result was shown in Table 5. Moreover, the external appearance at the time of resin layer extrusion was observed visually, and the good ((circle)) and no (*) were shown in Table 5. In addition, as an evaluation of extrusion moldability, the discharge pressure at the time of extrusion does not vary, the thickness variation in the longitudinal direction does not vary, and thin film molding is possible (good), thin film molding is possible, Those in which the thickness variation in the circumferential direction was slightly confirmed were evaluated as slightly inferior (Δ), and those incapable of forming a thin film were evaluated as inferior (×), and the results are shown in Table 5.

  In the EVOH-based composite resin of the resin layer in each example, the island phase of the elastomer is dispersed in the sea phase of the ethylene / vinyl alcohol copolymer, and the diameter is 0.04 to 0.00 mm in the island phase of the elastomer. An ethylene / vinyl alcohol copolymer of about 45 μm is dispersed in the form of scattered dots. Table 5 shows scattered dot-like dispersion ratios obtained by transmission electron microscope images and average dispersed particle diameters of the island phase of the elastomer. It was street.

  From Table 5, it can be seen that there are suitable ranges for the average acid value of the elastomer used and the acid value of the modified elastomer.

It is a perspective view which shows embodiment of the hose for refrigerant | coolant transportation of this invention. It is a perspective view which shows other embodiment of the hose for refrigerant | coolant transportation of this invention. It is a perspective view which shows other embodiment of the resin layer of the hose for refrigerant | coolant transport which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Resin layer 1A, 1B, 1C, 1D Laminated resin layer 1a-1, 1a-2, 1a-3 1st resin layer 1b, 1b-1, 1b-2 2nd resin layer 2 Inner tube rubber layer 3 Reinforcement Yarn Layer 3A First Reinforcement Yarn Layer 3B Second Reinforcement Yarn Layer 4 Intermediate Rubber Layer 5 Outer Rubber 6 Inner Rubber Layer 10, 10A Refrigerant Transport Hose

Claims (9)

  An EVOH composite resin comprising an ethylene / vinyl alcohol copolymer and an elastomer.   2. The EVOH composite resin according to claim 1, wherein the content of the elastomer is 10 to 45% by weight.   3. The EVOH composite resin according to claim 2, wherein the elastomer is a modified elastomer or a mixture of a modified elastomer and an unmodified elastomer.   The EVOH composite resin according to any one of claims 1 to 3, wherein the content of the modified elastomer is 20% by weight or less. 5. The EVOH composite resin according to claim 1, wherein an average acid value of the whole elastomer is ₃ to 7.5 mg-CH ₃ ONa / g. 6. The EVOH composite resin according to claim 3, wherein the modified elastomer has an acid value of ₃ to 15.0 mg-CH3ONa / g.   The sea phase is an ethylene / vinyl alcohol copolymer, the island phase is an elastomer, and the ethylene / vinyl alcohol copolymer is dispersed in the island phase of the elastomer according to any one of claims 1 to 6. An EVOH-based composite resin characterized by being dispersed in the form of dots.   8. The EVOH composite resin according to claim 1, wherein the ethylene / vinyl alcohol copolymer has an ethylene content of 28 to 40 mol%.   A refrigerant transport hose comprising a layer made of the EVOH composite resin according to any one of claims 1 to 8.

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